Hyperspectral Analysis of Submerged Aquatic Vegetation

The Science Issue and Relevance
Hyperspectral Imaging (HSI) separates light and other forms of electromagnetic energy into numerous narrow bands usually measuring only a few nanometers each in width. This presents the advantage of measuring the precise interaction of photons with a target material. It is a fundamental form of chemometric analysis and is commonly used in laboratory chemistry. HSI captures these narrow bands in numerous, often hundreds of separate images, each representing sometimes unique fingerprints of materials and processes. The overall goal of this investigation is to evaluate vegetative species composition and extent, as well as emerging threats to the lotic (i.e., flowing water) ecosystems in these parks. Assessments of aquatic vegetation and algae are important for monitoring riverine ecosystem integrity and can alert National Park Service (NPS) managers to water quality degradation and eutrophication from upland land uses outside the park boundary. Aquatic vegetation serves as a food source and microhabitat for stream invertebrates and provides critical feeding and cover habitat for fish.

Methodology for Addressing the Issue
Working in cooperation with the NPS and the Western Pennsylvania Conservancy, USGS scientists are utilizing hyperspectral data from the Civil Air Patrol (CAP) ARCHER (Airborne Real-time Cueing Hyperspectral Enhanced Reconnaissance) systems to map submerged aquatic vegetation (SAV), along with the invasive algae Didymosphenia geminata (didymo, a.k.a. "rock snot"), in the Delaware Water Gap National Recreation Area and Upper Delaware Scenic and Recreational River.

Future Steps Field work and additional data collection, especially in situ spectral data of submerged aquatic vegetation (SAV), will help refine the spectral "signatures" of SAV and will assist National Park Service managers in the protection of sensitive aquatic resources.